Is it better to read The Decagon House Murders having already read Ayatsuji's original novel or not? I asked myself that question a lot while reading. Partly this is because there are some significant changes here for an otherwise fairly faithful adaptation, although they won't necessarily impact the story – Doyle's gender is changed (she was a he in the novel), the story has been moved from the late 1980s to 2018, and some of the omnipresent decagons have been omitted, presumably to save the artist's sanity. All of these small details make sense, even Doyle's change in gender, which adds a female character to an otherwise male-dominated cast. And in either case, it does seem like it will be worth exploring this manga version even if you're already familiar with the novel's plot, because one of the great things about re-reading a mystery is that once you know whodunit, you can spend time reveling in the clues you may have missed the first time around.

On that subject, one of the positives to updating the story by forty years is that the manga gives more background into who the authors each character is named for are, since not everyone is up on their Golden Age and Victorian mystery authors and the manga is trying to reach a broader audience than the original novel did. While we can safely assume that most people have heard of Edgar Allen Poe and Agatha Christie, today Gaston Leroux isn't primarily associated with the mystery genre (assuming people remember that The Phantom of the Opera was originally a book) and Ellery Queen and S. S. Van Dine are mostly only known by mystery buffs. That said, a couple of important details are left out of the synopses of those last two, namely that Ellery Queen (pseudonym of Jewish immigrant cousins Frederic Dannay and Manfred Lee) was one of the major voices advocating for the fair play mystery and that S. S. Van Dine not only wrote the Philo Vance series, he created a list of twenty genre rules – all of which are followed in at least the source novel. This added information allows artist Hiro Kiyohara to play around with some of the character designs in order to incorporate elements of their books, like Leroux's yellow hoodie as a reference to Gaston Leroux's Mystery of the Yellow Room, to say nothing of Doyle's 221B sweatshirt. There's another element in the art that's particularly well done, too, but that would be a major spoiler to reveal; suffice it to say that I'm impressed.

The pacing of this volume feels comparable with the novel, which is good, although we're spending more time with those on the mainland than on the island. Since the book ends with the first murder, however, it seems likely that the balance will be better maintained in the next volume – because after all, the detectives must have a crime to investigate. That's where this story (both novel and manga) is particularly interesting: we have two separate sets of detectives investigating related crimes unbeknownst to each other. On the island, the students are curious about the deaths at the Blue Mansion (the name of which isn't explained in the manga; like the Decagon House's name scheme, everything in the mansion was blue), but then the plates labeled “victim[s] 1 – 5,” “detective,” and “murderer” appear, with the volume culminating in the first death. Meanwhile on the mainland, two members of the club who did not go – one current and one former – receive letters from the architect who died on the island six months ago, claiming that a deceased club member, his daughter Chiori, was murdered. That's what Doyle begins looking into with the help of another club member as the armchair detective and a Buddhist monk. Doyle is aware of the link between Tsunojima and Chiori, but the members on the island are not, and in fact they don't even know that the letters have been delivered. Is there a tie between the two cases? And what will the island group's ignorance of the letters mean for them?

It is worth noting that Chiori's Manner of Death has also changed between novel and manga, and that does make a little less sense than some of the other alterations. In the book, Chiori dies of alcohol poisoning at a club event; in the manga she drowns when a boat capsizes during a club outing. This may be an effort to link the island and Chiori more closely – there's no bridge or ferry, so it's only accessible by smaller craft – but it could also be part of the effort to reframe elements of the book for a wider, and perhaps younger, audience. That will, hopefully, eventually come clear; from the fact that island club members make reference to “fretting about that” and a few flashbacks, it looks as if this could be an attempt to add in another reference to And Then There Were None, Ayatsuji's main influence, specifically by linking Ellery to Vera Claythorne.

On the whole, this volume feels like it's working well with its source. The art definitely helps with that; although faces can be a little off-putting, the backgrounds are spectacular and everyone's body language is very well done, especially Doyle, whose restlessness is easily seen from her ever-shifting positions when she's sitting or standing. There are also a few oblique references to Van Dine's rules, such as when Poe directly mentions a potential answer to the mystery that's in violation of Rule Four, reminding us that Ayatsuji is, in fact, playing by the rules. Whether you've read the original novel or not, the manga is a treat for mystery fans, although familiarity with basic tenets of Golden Age Mystery (roughly the between-the-wars period in the 20th century), Van Dine's rules, and And Then There Were None will all enhance your reading experience. There's a least one game afoot in the series, and it's one worth playing.